Inflammation is a key component of Coronary Artery Disease (CAD) and a primary driver of Acute Myocardial Infarction (AMI). In animal models, various B lymphocyte subsets are known to modulate inflammation in CAD and AMI, however limited data exists exploring B lymphocytes in clinical context. The aim of this study was to clinically characterise the B lymphocyte subsets from peripheral blood in CAD disease progression.
We recruited 12 healthy subjects, 12 stable CAD patients and 12 AMI patients. Blood samples were drawn from all participants and analysed by flow cytometry for the major peripheral B lymphocyte subsets including transitional, naïve, Antibody Secreting Cells (ASCs), memory populations (including switched, unswitched, IgD-only and IgM-only) and Double Negative populations (including DN1 and DN2).
We identified a significant shift in peripheral ASCs in AMI subjects (median 0.51% (IQR 0.25-0.83) of total B lymphocytes), compared to healthy subjects (1.45% (0.73 – 2.18); p=0.01). No other subset of B lymphocytes displayed a significant change between the healthy, stable CAD and AMI subjects.
We observed an absence of change in a majority of peripheral B lymphocyte subsets across these three groups. ASCs were the only subset to be reduced significantly in subjects with AMI, compared to healthy subjects. This difference may be reflective of ASCs returning to lymphatic structures due to immunological signalling following an AMI. Comparing the phenotype and functional responses of B lymphocytes from the periphery with B lymphocytes in lymphatic tissues central to the myocardium may shed more light on how B lymphocyte subsets change in response to AMI. These studies will allow us to enrich our clinical understanding of the B lymphocyte response in CAD progression.